text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2018 The Stdlib Authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *    http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
  
  'use strict';
  
  // MODULES //
  
  var tape = require( 'tape' );
  var isnan = require( '@stdlib/math-base-assert-is-nan' );
  var gamma = require( '@stdlib/math-base-special-gamma' );
  var abs = require( '@stdlib/math-base-special-abs' );
  var incrspace = require( '@stdlib/array-base-incrspace' );
  var EPS = require( '@stdlib/constants-float64-eps' );
  var gamma1pm1 = require( './../lib' );
  
  
  // FIXTURES //
  
  var smallPositive = require( './fixtures/cpp/small_positive.json' );
  var smallNegative = require( './fixtures/cpp/small_negative.json' );
  
  
  // TESTS //
  
  tape( 'main export is a function', function test( t ) {
  	t.ok( true, __filename );
  	t.equal( typeof gamma1pm1, 'function', 'main export is a function' );
  	t.end();
  });
  
  tape( 'the function computes `gamma(x+1) - 1` for most `x` (negative)', function test( t ) {
  	var expected;
  	var val;
  	var x;
  	var y;
  	var i;
  	x = incrspace( -170.5, -0.5, 0.5 );
  	for ( i = 0; i < x.length; i++ ) {
  		// Add 0.1, as the gamma function is not defined for negative integers:
  		val = x[ i ] + 0.1;
  		y = gamma1pm1( val );
  		expected = gamma( val+1.0 ) - 1.0;
  		t.equal( y, expected, 'returns expected value' );
  	}
  	t.end();
  });
  
  tape( 'the function computes `gamma(x+1) - 1` for most `x` (positive)', function test( t ) {
  	var expected;
  	var val;
  	var x;
  	var y;
  	var i;
  	x = incrspace( 2.0, 170.5, 0.5 );
  	for ( i = 0; i < x.length; i++ ) {
  		val = x[ i ];
  		y = gamma1pm1( val );
  		expected = gamma( val+1.0 ) - 1.0;
  		t.equal( y, expected, 'returns expected value' );
  	}
  	t.end();
  });
  
  tape( 'the function accurately computes `gamma(x+1) - 1` for small negative numbers', function test( t ) {
  	var expected;
  	var delta;
  	var tol;
  	var x;
  	var v;
  	var i;
  
  	x = smallNegative.x;
  	expected = smallNegative.expected;
  
  	for ( i = 0; i < x.length; i++ ) {
  		v = gamma1pm1( x[ i ] );
  		delta = abs( v - expected[ i ] );
  		tol = 5.0 * EPS * abs( expected[ i ] );
  		t.ok( delta <= tol, 'within tolerance. x: ' + x[ i ] + '. Value: ' + v + '. E: ' + expected[ i ] + '. Δ: ' + delta + '. tol: ' + tol + '.' );
  	}
  	t.end();
  });
  
  tape( 'the function accurately computes `gamma(x+1) - 1` for small positive numbers', function test( t ) {
  	var expected;
  	var delta;
  	var tol;
  	var x;
  	var v;
  	var i;
  
  	x = smallPositive.x;
  	expected = smallPositive.expected;
  
  	for ( i = 0; i < x.length; i++ ) {
  		v = gamma1pm1( x[ i ] );
  		delta = abs( v - expected[ i ] );
  		tol = 2.0 * EPS * abs( expected[ i ] );
  		t.ok( delta <= tol, 'within tolerance. x: ' + x[ i ] + '. Value: ' + v + '. E: ' + expected[ i ] + '. Δ: ' + delta + '. tol: ' + tol + '.' );
  	}
  	t.end();
  });
  
  tape( 'the function returns `NaN` if provided `NaN`', function test( t ) {
  	var val = gamma1pm1( NaN );
  	t.equal( isnan( val ), true, 'equals NaN' );
  	t.end();
  });
  